Updated registry disk docs to build off of the proper image.
Updated registry disk docs to build off of the proper image.

Signed-off-by: Dylan Redding <9e34a07e7b08d4e999b011807b985d106d8b9298@gmail.com>

stu-gott/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,davidvossel/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt